View Full Version : Wiring vs. output: Basic Question
05-04-2012, 11:11 AM
What happens to the sensitivity (or the output) of drivers when they are wired in series/parallel?
2 Woofers @ 89 db / 1 watt wired in series = ??? db / 1 watt
2 woffers @ 89 db / 1 watt wired in parallel = ??? db / 1 watt
I understand how this works in reagrds to Ohms, just not output.
There's a difference between sensitivity and efficiency. Efficiency is generally described as the sound pressure level measured at 1m with a 1 watt input, whereas sensitivity is SPL measured at 1m with a 2.83V input (which will produce 1 watt across an 8 ohm load). In your example, both scenarios would produce efficiencies of 92dB/1m/1W. However their sensitivities would be 89dB/1m/2.83V (series) and 95dB/1m/2.83V (parallel).
It's all about impedence.
- series impedence = 2x driver, so 1/2 the power draw at constant voltage
- parallel impedence = 1/2 driver, so 2x power draw at constant voltage.
The second driver will double cone area, yielding +3dB.
- In series, the higher impedence reduces power draw by -3dB, thus it's a wash.
- in parallel, the lower impedence increases power draw by +3dB, for a total of +6dB in voltage sensitivity.
The way to look at it is that amps produce voltage gain, and then try to keep up with the resulting current draw. A 4 ohm and a 16 ohm speaker connected to the same amp will have the same voltage at the terminals, but one will draw 4x the current - V=IR all the time.
Now, to be absolutely correct, efficiency is a power question - electrical watts converted into acoustic watts - while sensitivity is more of a response question that I'm still learning about.
05-04-2012, 01:05 PM
Just when you think you're starting to get the hang of things... hahaha. I love this stuff. Great info guys, I really appreciate it.
Are there any websites, or online resources you could reccomend that deal with this subject?
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